(BAT) Reference Document for the Production of Chlor-alkali ...

Chapter 2
Source: [ 147, Arkema 2011 ]
Figure 2.18: View of a chlorine absorption unit
The purpose of a typical chlorine absorption system is two-fold:
To continuously absorb chlorine gas arising in streams such as tail gas from liquefaction, air
blown from waste brine or chlorine condensate dechlorination or and also wet and dry
maintenance headers. Up to 5 % but normally less than 1 % of the plant production is
absorbed in this way.
To absorb the full cell room production during emergency for an adequate period, usually
not less than 15 to 30 minutes, to enable corrective measures to be taken or the plant to be
shut down in a safe manner. Gravity-fed head tanks or pumps supplied with backup power
supplies may be used to give increased reliability and operation under power failure
conditions.
The above functions could be undertaken in separate purpose-built units, providing the integrity
of the systems is maintained by having backup scrubbers. The aforementioned purposes can be
achieved by using one or several systems, usually composed of several absorption units placed
in series or in parallel to ensure a high level of availablility by redundancy. Some additional
equipment is often installed as back up. Packed towers and/or ejector systems are usually used
in the absorption unit [ 3, Euro Chlor 2011 ].
WORKING DRAFT IN PROGRESS
56 December 2011 TB/EIPPCB/CAK_Draft_1